Some PCV Valve Questions

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Doc Pepper
Posts: 625
Joined: July 21, 2006, 1:26 pm
Location: AZ

Some PCV Valve Questions

Post by Doc Pepper »

Operation wise, how do you know your PCV valve is bad? 100,000 miles ago, I installed my rebuilt motor, but I could not get the original PCV valve out of the valve cover, so I simple left it in. Over the years, I noticed that my engine seemed to always have layers of grease and muck all over it. I never had a vehicle with such a dirty engine. Although I suspected that the PCV valve might be the culprit, I still could not get that thing out of the valve cover.
Finally, during this last fiasco with the fuel pump and carburetor, I took a vise grip and two pry bars to the PCV valve and was able to get it out.
The first thing I noticed was that it had a lower lip on it that held it in place in the grommet in the valve cover. The replacement did not have that lower lip and, as a result, went right in.
Second, the old PCV valve was, ... uhm, ... , quite clogged.
Obviously, you can tell the condition of a PCV valve when you are holding it in you hand and you can see inside it and shake it.
But, how can you verify its operation while it is still in the engine.
Another observation: The distributor that I replaced last week also had a terrific amount of greasy residue on it, which was probably what caused it to fail. As soon as the temperature outside drops below 112 degrees, I will take the truck to a car wash and clean off the grease on the motor. I am curious if it was a result of the valve.
And before I forget, does anybody know if we can still get the molded rubber PCV valve hoses anymore?
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bobenhotep
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Re: Some PCV Valve Questions

Post by bobenhotep »

I think you can still get them. I made one out of a piece of metal tubing with a bit of rubber on each end. I have all of the tubing benders for that type of stuff. I always cleaned my pcv valve on my old carburetor type vehicles with carb cleaner every year when I checked the settings and cleaned the carb. If the valve moves freely and the spring returns it to the neutral position, it should be good. If in doubt buy a new one.

If the PCV valve is blocked it will make the engine leak worse than normal. The valve evacuates the blow by gasses, and reduces blow by pressure. In addition, the engine burns blow by gasses (basically a little extra free fuel) instead of venting them.
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Doc Pepper
Posts: 625
Joined: July 21, 2006, 1:26 pm
Location: AZ

Re: Some PCV Valve Questions

Post by Doc Pepper »

Ever since I changed the PCV valve, the engine has been running nicer (I did have to enrich the idle), and that layer of scum and grease has disappeared from the top of my motor.
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